Means for preventing the distortion of bucket-wheels.



PATENTED SEPT. 11, 1906.

W. L. R. EMMET.

MEANS FOR PREVENTING THE DISTORTION 0P BUCKET WHEELS.

APPLICATION 'I'ILBD MAY 6, 1904.

2 SHEETS-SHEET 1.

Fig.5.

Witnesses.

PATENTED SEPT. 11

W. L. RLBMMET. MEANS FOR PREVENTING THE DISTORTIION 0F BUCKET WHEELS.

, APPLICATION FILED KAY 6, 1904.

2 SHEETS-SHEET 2.

Inventor: William L.F?.Emmeb,

Witnesses:

ITED- STATES PATENT OFFIGE.

IVILLIAM' L. It. EMMET, OF SOHENECTADY, NEW YORK, ASSIGNOR TO GENERALELECTRIC COMPANY, A CORPORATION OF NEW YORK.

lnEANS FOR PREVENTING THE DISTORTION OF BUCKET-WHEELS.

Specification of Letters Patent.

Patented Sept. '11, 1906.

Application filed May 6. 1904- Serial No. 206,709-

I s It has been found in connection with elastic-fluid turbines, andparticularly in those having wheels of large diameters, that when inoperation a difference exists in the mean temperature on oppositesidesof the wheel,

and, further, that this difference varies under different conditions ofoperation. .This temperature diflerence is sometimes noticeable instarting the turbine, as well as during its normal operation, and isusually detected by the sound occasioned by the rubbing of therelatively rotating parts. In other words, the temperature on one sideof the wheel may be greater than on the other, and when this differenceexceeds a certain amount it causes a prohibitive distortion or Warpingof the wheel parts. The diflerence in temperature is largely due to thefact that the tem erature of the steam or other motive fluid lea ingthrough the clearances between the nozzles or other discharging devicesand the buckets and also around the shaft is above that discharged fromthe wheel, the said leakage being frequently in a superheated condition.The temperature diflerence is also due to radiation from the adjacentwall or diaphragm of the stage of higher pressure. Another reason forthis difference is found inconnection with. those stages where by reasonof their construction a difference in pressure exists on opposite sidesof the wheel. My observation in connection with vertical-shaft machineshaving wheels occupying horizontal planes with the flow of motive fluiddownward in an axial direction is that the excess temperature on the uper side may cause a downward deflection o-the wheel, thereby causingthe buckets on the exhaust side to rub unless the clearances areexcessive. The same action may take place in horizontal machines; but insuch event the distortion is in a horizontal or approximately horizontaldirection instead of. vertical or approximately vertical direction. Thedeflection is more noticeable in the last wheel of"a turbine, whereinthe active area of the at a more nearly uniform temperature.

from warping or distorting the wheel.

wheel is greateras, for example, when the nozzles and intermediatescover the entire or substantially the entire circumference of the wheelbut it also takes place in other wheels located in stages orcompartments of higher pressure.

Broadly, my invention contemplates the idea of preventing or reducingthis distor: tion to a point where it can be disregarded by protectingthe surface or surfaces of a turbine which are normally exposed tomotive fluid by a suitable covering or mask applied surfaces will beless susceptible to temperature effects.

My invention also broadly contemplates the idea of compensating whollyor in part for any tendency which the turbine part or parts may have towarp or distort, due to unequal temperature effects.

. The invention is applicable to turbines having one or a number ofwheels in the at any suitable place or places, so that said same orseparate compartments, and I do not limit myself to any particular wheelconstruction, either as to the body of the wheel or to the arrangementof the buckets. Neither do I limit myself to the character orarrangement of the devices which supply motive fluid to the wheel or tothe controlling 'mechanism or to the arrangement of the buckets.

The particular wheel or wheels to be prochambers which further serve toprevent distortion by causing the entire wheel to operate To made insingle I state the matter differently, the covering and chambers,considered together or separately, act to prevent sudden temperaturechan gs e temperature of thewheel as a whole can be increased ordecreased, as. desired; but the changes should be brought about in sucha manner. Between the covering and themanner that no substantialdifference exists at any given instant of time on those surfaces whichare capable of causin distortion.

In order to compensate or any tendency to distortion which may existunder varying conditions of operation, I may connect one or all of thechambers with one or moresources of fluid-pressure which is capable ofchanging the temperature of the wheel parts to a certain extent. Thearrangement of the chambers and supply-passages should be suchthat ,theeffect of the fluid is readily felt over 'those' surfaces which arecapable of causing distortion. The chambers may be formed at the timethe wheel is made or they maybe formed inha bluilt-up structure that isattached to the w ee Y In order to carry out the invention withexlstlngconstructlons, a

'dlsk or covering, usually of metal, may be mounted on the in let sideof thewheel which covers theentire surface or a large portion of saidsurface.

main body or web ofthe wheel is a' chamber which may or may not containa heat-resist-' ing medium, or in certain cases a cooling me-- dium maybe introduced. On the exhaust side of the wheel isa suitable coveringwhich protects that side of the Wheel from the Bf. fects of the steam orother elastic fluid in the compartment in which the wheel is'located.

The covering may and preferably should cover all ora very large portionof its surface. Between the covering and the main body or web of thewheel is preferably a chamber of suitable size. This chamber is adaptedto receive a heated medium-such, for example, as the motive fluidforincreasin the mean temperature of the exhaust side o the wheel, Thefluid may enter the chamber in any suit able way'. I have shown two suchways. In one case the fluid enters through one or more openings orpassages formed in the web of the wheel and in the other case throughone or more passages formed in the hub of the wheel. These latterpassages are arranged to receive the fluid'whieh leaks from one stage toan other around the packing's. In this manner the leakage fluid isrendered more effective than heretofore and any tendency towarping ordistortion compensated for. Arranged at one or more suitable andpreferably out of line with the inlet-passage, are passages or openingsthrough which the fluid escapes after having given up its heat or acertain per cent. thereof to the sur faces of the wheel. The fluid thusescaping from one wheel discharges into a comparttwo paths, the normalor main path through the nozzles, wheel, buckets, and intermediate ointsin the covering,

buckets, where the latter are used, and an auxiliary path conveying asmall portion of the fluid for heating purposes alone. The main andauxiliary paths are arranged in multiple, the former being of relativelylow resistance and the latter of relatively high resistance.

It is desirable to cover both the admission and exhaust sides of thewheel, but the covering onthe admission side can be omitted undercertain conditions, and I aim to embrace this arrangement in the claims.

In the accom anying drawings,which illustrate one eml iodiment of myinvention, Figure 1 is a partial vertical section of a jetturbine of themultistage type having two rows'of wheel-buckets per stage. Fig. 2 is atransverse section of the same. Fig '3 is a detail sectional viewshowing the arrangement of the inlet and outlet ports or passagesv forconveying motive fluid into and out of the chamber on the exhaust sideof the wheel, and Fig. 4 is a detail perspective view of one of thechannel-irons employed to support the covering. v

1 represents the main shaft, upon which are mounted'one or morebucket-carrying Wheels 2 Eachof these wheels is provided with one ormore rows of buckets 3. In the present instance each wheel isprovidedwith two rows of buckets. v shown in the present construction, which areinclosed in a casing 4, made up of suitable sections. The wheels areseparated one from the other by diaphragms 5, which 100 divide theeasing into compartments, a single wheel being located in eachcompartment. Between the diaphragms and the shaft or the hub ofthe wheelis anacking 6 for reducing the leakage between the wheel-compartment andthe next. Steam or other elastic fluid is supplied to the wheel-bucketsby a valvechest -7, which is connected to the source of supply. Mountedin the valve-chest are a number of valves 8, each of which is actuated apiston 9, that is or may be under the control of a relay-valve, thelatter being controlled by a speed-responsive device. Each valvecontrols the passage of fluid to one or more nozzles or nozzle-sections9, which in turn discharge the fluid at the proper angle against thebuckets. Where two or more rows of buckets are provided for each wheel,intermediate buckets 10 are provided be tween two rows ofwheel-buckets.The arrangement of the nozzles and buckets is the same throughout themachine, except that V the active p'ortionof the wheel graduallyenlargesfrom the inlet to the exhaust.

The wheel-casing is mounted on a base 11, which contains a chaml r 12,that is'corinected to a condenser or to the atmosphere, as is desired.Mounted on the upper surface of each wheel to be protected areconcentric rings or supports 13 and 14, which support F our wheels arethe protecting-covering 15, the latter being of disk-like formation andmade up of one or more pieces. In the present construction this coveringis made up of two sections of sheet metal riveted together, as shown inFig. 2. The covering is supported at intermed1 ate points bychannel-irons 16, shown in dotted lines in Fig. 2 and in perspective inFig. 4. On the under side of the wheel are attached concentricsupporting-rings 17 and 18, to which the covering 19 is attached. Thiscovering is supported at intermediate points by channel irons 20 of thesame character, as shown in Fig. '4. Between each of the coverings andthe web of the wheel is a chamber 21, the chamber on the upper side ofthe wheel acting simply as a dead-air space or chamber, while thechamber on the under side is connected to the steam-space above thewheel by one or more openings, passages, or conduits 22. In the presentillustration there are a number of circular openings near the peripheryof the wheel and other openings near the hub of the wheel. In additionto these are passages 23, formed in the hub of the Wheel, whichcommunicate with grooves formed in, the pack-ings 6, so that any'leakagethrough thepacking will be diverted into the chamber on the under sideof the wheel.

In order to permit the fluid to pass fromthe chamber either on the underor upper side of the wheel after giving up a certain amount of its heatto the Wheel parts or cooling it, as the case may be, one or moreopenings or passages 24, Fig. 3, are provided, the

said passages being offset from the inlet-passages to prevent the steamor other fluid .from passing directly from the inlet to the ,under sideof the wheel, but in some cases certain of these passages can beomitted.

- From actual tests of my invention I have found that objectionablewheel distortions can be obviated andthat'the compensation may even bein excess of that required and actually cause thebuckets to move upinstead of down. i

In accordance with the provisions of the patent statutes I havedescribed. the principle of operation of my invention, together with theapparatus which I now believe to represent the best embodiment thereof;but I desire to have it understood that the apparatus shown isonlyillustrative and that the invention can be carried out by other means.

What Iclaim as new, and desire to secure by Letters Patent of the UnitedStates, is-

1. A turbine comprising a casing and relatively movable parts, incombination with a protecting-covering attached to and moving with apart for preventing objectionable distortion thereof.

2. A turbine. comprising a caslng and a bucket-wheel, in combinationwith a protecting-covering applied to the web or body of the wheel.

3. A turbine'comprisinga casing and a bucket-wheel, in combination witha protecting-covering for the'web or body of the wheel and means forattaching the covering to the wheel.

4. A turbine comprising a casing and a bucket-wheel, in combination witha protecting-covering for both sides of the web or body of the wheel.

5. A turbine comprising a casing and a bucket-wheel, in combination witha protecting-covering for one side of the Wheel, and a chamber situatedbetween the covering and the Wheel.

6. A turbine comprising a casing and a bucket-wheel, in combination withprotecting-coverings for both sides of the wheel, and a chamber situatedbetween each covering and the wheel.

7. In a turbine, the combination of a casing, a chambered wheel, and aconduit for admittingfiuid to the chamber.

8. A turbine com rising a casing and a bucket-wheel, in com ination witha protective covering carried by the wheel for preventing it fromdistorting, said covering being independent of the bucket-supportingportion.

9. A turbine comprising a casing and a bucket-Wheel, in combination withchambers moving with the wheel and arranged to receive a fluid forequalizing the mean temperature on opposite sides of the wheel.

12. A turbine comprising a casing and a bucketwheel, in combination witha protecting-covering for one side of the wheel, containing a chamber,and an opening or passage for conveying a heat-imparting fluid to thechamber.

13. In a turbine, the combination of a casing, a chambered wheel,driving-buckets carried by the wheel, and an opening or passage forconveying motive fluid from one side of the wheel into the chamber.

14. In a turbine, the combination of a casing, a chambered wheel,driving-buckets car-. ried by the wheel, and an inlet and an outletopening or passage for the chamber.

15. In a turbine, the combination of a casing, a chambered wheel.buckets on the Wheel, nozzles discharging fluid against the buckets, aninlet opening or passage located nearthe periphery of the heel, and anoutlet opening or passagelocated at a point remote therefrom .forpreventing Wheel distor-' tion.

16. In a turbine, the'combination of a cas- 1 ing, a chambered Wheel,inlet-openings 10- cated near the center and near the periphery of theWheel, and outlet-openings located'between the inlet-openings.

17. In a turbine, the combination of a chambered bucket-wheel, a casingtherefor, a Wall situated Within and dividing the easing intocompartments, a packingfor reducing the leakage around the wheel-shaft,and a passage leading from the packing to the chamber in the Wheel.

'cated on opposite sides of the wheel for 18; A turbine comprising acasing anda bucket-Wheel, in combination with means 10- equalizing thetemperatures.-

. 19. In a steam-turbine, the combination of.

a chambered bucket-Wheel, a casing therefor, a device for protecting theinlet side of the Wheel from hot steam, and means for directing hotsteam against the exhaust side of the Wheel.

20. In a turbine, the combination of a Wheel, a casing therefor, bucketson the Wheel between Whichthe major portion of the motive fluid passesto produce rotation, and an auxiliary path through Whichthe motive fluidpasses to equalize the mean temperatures on opposite sides of the Wheel.

21. A turbine comprising a casing and relatively movable parts, bucketscarried by one of the parts, and devices for discharging fluid againstthe buckets, in combination with a hand this 5th day of May, 1904.

WILLIAM L. R. Ei/niET.

Witnesses BENJAMIN B. HULL, HELEN ORFOBD.

